DESCRIPTION Understanding and optimizing the transport and delivery of oligonucleotides to targets in vitro and in vivo is a major problem for the field of antisense therapeutics. This proposal addresses two aspects of the oligonucleotide therapeutics. Of the oligonucleotide transport and delivery problem. In specific aim 1, the applicant propose to develop methods to enhance the intracellular accumulation and pharmacological effectiveness of the antisense oligonucleotides. This will emphasize (1) novel "delivery peptides" based on consensus sequences developed from the tat attenadepia, and K-FGF signal peptides; and (2) a variety of polyamine dendritic polymers. In collaboration with Dr. Shaw of Duke University, Dr. Juliano plans to synthesize over 100 chimeric oligo- peptides and evaluate each. The pharmacological effects of enhanced delivery will be screened using a novel reporter gene assay developed by Drs. Kole and Cho in which a positive effect on intron splicing will be observed if the Oligomer is active. Cellular uptake and sub-cellular distribution will be evaluated with fluorescent-tagged oligomers by confocal microscopic imaging techniques, using the resources of the Analytical Core Promising leads will be followed up in more stringent cancer-related in vitro models including multi-drug resistant 3T3 cells and ras-transformed carcinoma cells. In specific aim 2, the pharmacokinetics, tissue and tumor accumulation, metabolism and sub- cellular distribution of intravenous or intra-peritoneal administered oligonucleotides (radio-labeled or un-labeled) in mice bearing human tumor xenografts will be examined. Samples will be analyzed by capillary gel electrophoresis using the facilities of the Analytical Core. In specific aim 3, the therapeutic effect of enhanced delivery to tumors and tissues will be evaluated. The most promising agents generated in specific aim 1 will be used to down-regulate Ki-ras expression in a ras-dependent colonic carcinoma xenograft model. In addition, a transgenic mouse model produced by Dr. Kole will also be evaluated. In this model, the expression of EGFP in tissues will be activated only when antisense oligonucleotide causes splicing out of an intron inserted into the CGFP gene.